Undo work done (transactional).
  
  Syntax:
ROLLBACK [WORK] [TO [SAVEPOINT]'savepoint_text_identifier']; ROLLBACK [WORK] [FORCE 'force_text'];
FORCE - will manually rollback an in-doubt distributed 
  transaction
  
  "One of the symptoms of an approaching nervous breakdown is the belief that 
  one's work is terribly important" ~ Bertrand 
  Russell 
  
Related Oracle Commands:
COMMIT - Save Changes
LOCK TABLE
 SAVEPOINT - Save changes to a point
DBMS_FLASHBACK 
Syntax - Redo, Rollback and Undo
Related Views:
V$TRANSACTION V$TRANSACTION_ENQUEUE V$GLOBAL_TRANSACTION V$ROLLSTAT